The newly described creature, nearly 18 inches long, appears to have been a "living fossil" in its own time some 125 million years ago. By then, its direct ancestors already had been around for 70 million years. They shared a common ancestor with the likes of bony-plated creatures such as Stegosaurus and Triceratops.
It's the third of three fossil finds this week that have generated superlatives.
On Monday, a team of scientists in Norway and the United States announced the discovery of "Predator X," a 50-foot-long, 45-ton ocean creature that scientists say ruled the seas some 147 million years ago. Paleontologists with University of Oslo's Natural History Museum unearthed the fossil remains of the four-flippered predator last year from beneath the permafrost on Svalbard, a cluster of islands above the Arctic Circle.
At the other end of the size scale, a pair of Canadian paleontologists reported on Tuesday the discovery of the smallest nonbird meat-eater yet found in North America. The 75-million-year-old fossil remains of the dinosaur, by some estimates roughly the size of a small chicken, were unearthed in 1982 from the Dinosaur Park Formation in Alberta. But no one gave the specimen a serious look until 2007. The results appeared in this week's issue of the Proceedings of the National Academy of Sciences.